Cutting red meat intake could lengthen lifespan, Harvard study finds

Americans’ high consumption of red meat has long been linked to a host of health problems, including heart disease, diabetes, and cancer, and new research from the Harvard School of Public Health suggests that it may shorten a person’s lifespan and that cutting back on red meat by a serving a day could lower the risk of dying.

A second study from the same research group, also published Monday, links sugary beverages to a higher rate of heart disease.

“That Happy Meal choice of a hamburger with a Coke is quadruply bad for your health,” said Dr. Walter Willett, chairman of the nutrition department at the Harvard School of Public Health and co-author of both studies.

Advertisement - Continue Reading Below

In the first paper, published in the Archives of Internal Medicine, the researchers periodically conducted dietary surveys of 121,000 physicians and nurses over more than two decades and found that those who ate the most red meat—more than two three-ounce servings per day—had about a 30 percent greater likelihood of dying over the course of the study compared with those who ate about one to two servings per week.

“With evidence piling up against red meat, the associations we found were not surprising,” said Dr. Frank Hu, a Harvard professor of nutrition and epidemiology who was also a co-author of both studies. “What surprised us was the magnitude of the association. I think it should convince people to change to a more plant-based diet where red meat isn’t major component.”

The second study, published in the journal Circulation, examined the dietary habits of 43,000 male health professionals—part of the same group involved in the meat study—and found that men who consumed more than six servings a day of sugar-sweetened soda, fruit juice, and sports drinks had a 20 percent greater risk of having a heart attack over 22 years compared with those who rarely drank them or drank low-calorie, artificially-sweetened drinks.

The statistical associations made in the red meat and beverage studies don’t prove that these two dietary factors actually caused negative health outcomes, but the links remained after researchers took into account a variety of other factors that might have also contributed, such as body weight, smoking habits, hypertension, and diabetes.

Volunteers in the meat study who reported eating the most processed red meat, such as bacon, salami, hot dogs, and sausages, had a higher risk of dying from cancer and heart disease than those who ate mainly steak or meatballs. But both groups of red-meat eaters had a higher risk of dying compared with those whose diets relied upon other sources of protein such as fish, chicken, nuts, or low-fat dairy products.

In fact, the researchers calculated that hearty meat eaters could reduce their risk of dying from 7 to 19 percent by substituting one meat serving a day with other sources of protein.

“Plant-based foods are rich in phytochemicals, bioflavonoids, and other substances that are protective,” wrote Dr. Dean Ornish, head of the nonprofit Preventive Medicine Research Institute in Sausalito, Calif., in an editorial that accompanied the meat study. “In other words, what we include in our diet is as important as what we exclude, so substituting healthier foods for red meat provides a double benefit to our health.”

While red meat tends to contain more cholesterol-raising saturated fat than other protein sources, it also has heme iron that may produce cell-damaging compounds, and it forms carcinogenic substances when cooked; processed meat has high levels of sodium, nitrates, and other preservatives.

Sugar-sweetened beverages can contribute hundreds of calories a day to the diet, increasing the risk of obesity and related problems, including type 2 diabetes and heart disease. The men who drank the most sugary beverages in the Circulation study had higher levels of triglycerides, a component of cholesterol associated with diabetes, and markers of heart-damaging inflammation and had lower levels of the heart-protective cholesterol, HDL.

“The results mirror those previously reported … and add to the growing body of information that suggests an independent association between sugar-sweetened beverages and worse cardiovascular health,” wrote Northwestern University cardiologist Dr. Mark Huffman in an editorial published with the study.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.